1. The Field of the Invention
The invention pertains to the field of power generation from aqueous electrolytic solutions by means of the osmosis phenomenon. Specifically, the invention introduces a unique process concept for maximizing the electric power generated by means of chemical potential dissimilarity of solutions, employing series of cells, each forming a closed hydraulic loop, and operating in symbiotic mode within a concentration potential field.
In general, this invention particularly promotes the concept of Large Scale Renewable Energy (LSRE) technology for producing power anywhere natural or manmade physical domain or ecological topography allows for cycling of waters of dissimilar salt concentration, preferably via accumulation-evaporation by natural renewable resources. This invention encompasses power generation from world endorheic (dead ended) saline and dry salt lakes as well as formulated ionizable inorganic salt solutions. Further, the invention pertains to novel applications such as pumping desalinated water to high altitudes, extracting water from brackish streams and concentrating fluids containing solids of commercial value without heat.
2. Definitions of Claimed Invention
Osmosis is the spontaneous movement of water, through a semipermeable membrane that is permeable to water but impermeable to solute, where water moves from a solution in which solute is less concentrated to a solution in which solute is more concentrated.
The driving force of the flow movement is the difference in the chemical potential on the two sides of the semipermeable membrane, with the solvent moving from a region of higher potential (generally a lower solute concentration) to the region of lower potential (generally higher solute concentration).
“Chemical Potential” appears to be an ambiguous and elusive terminology. In fact, it is one of the most important partial molal quantities. It is the energy potential associated with the activity of the ions of an ionizable substance. It is equal to the rate of change of system's free energy, known as Gibbs free energy, of a system containing a number of moles of such substance, when all other system parameters; temperature, pressure and other components are held constant. Simply, chemical potential is a form of energy like other kinds of potential; electrical, gravitational, momentum, magnetic, surface tension, etc. where, it is spontaneous and in the direction from high to low.
The difference in chemical potential of a substance in two adjacent phases separated by a semipermeable membrane determines the direction in which the substance diffuses spontaneously. When the components of a mixture have the same chemical potential no chemical transport or reaction takes place, and no mutual diffusion will occur, because there is no driving force. The chemical potential is an intensive property of a substance in a phase.
To prevent this movement of water across the semipermeable membrane, a pressure has to be imposed to equalize the force created by the difference in the chemical potential of the solution across said membrane. This force is named osmotic pressure. If the imposed pressure exceeds this limit, then water begins to flow from the region of higher solute concentration to the region of lower solute concentration. In this case, the force is named reverse osmosis pressure.
Regarding the title of this invention, the inventor believes that osmosis is nature's gift to life. It is the vehicle to transport fluids in all living cells and without it, all biological functions and all forms of life ceases to exist! This phenomenon is attracting the attention of researchers as a means to generate power. They tend to describe it in industrial terms such as forward osmosis, ordinary osmosis, direct osmosis, pressure retarded osmosis, etc.
In order to harness this natural phenomenon, the inventor believes that relevant potential fields should be established to induce and bring about the wonders of this phenomenon. Therefore, the inventor prefers to describe all applications that utilize the power of osmosis for the benefit of mankind as “Induced Osmosis”.
Further, the term symbiosis although a biological phenomenon, its generic or metaphorical concept refers to a mutually relationship of cyclic reverberation, without altering or modifying any of the specific components of the involved systems. In industrial applications, symbiosis is a process whereby a waste or less valuable byproduct in one industry is turned into a resource for use in one or more other industries. In essence, it is the process of optimizing functions of interrelated systems and achieves their ultimate availability.
Therefore, the inventor is naming the process of using osmosis in interrelated sequence of power generation cells as “Induced Symbiotic Osmosis” and is abbreviated here by the acronym “ISO”.
3. The Prior Art
The history of exploring osmosis started about 300 years ago. In 1748 Jean-Antoine Nollet, a French clergyman and experimental physicist was the first to conduct research in the theory of electrical attraction and repulsion of electrical matter between charged bodies that led him to the discovery of the osmosis of water through a bladder into alcohol. In 1855, Adolph Fick a German mathematician and physicist created a cellulose nitrate (nitrocellulose) membrane as the first synthetic membrane. In 1866, Thomas Graham a British physical chemist first used the term dialysis.
In 1867, Moritz Traube discovered that synthetic material such as copper Ferro-cyanide has desired properties as membrane material, which led Wilhelm Friedrich Philipp Pfeiffer, in 1877, to use such compound in a ceramic wall material to study osmotic equilibrium pressure. In 1901, Jacobus Henricus van't Hoff was awarded Nobel Prize for developing his theory of solutions. Van't Hoff introduced the term semipermeable membranes (halb durchläβige Wand), which are permeable only to one component of a binary solution.
In 1960—Sidney Loeb and Srinivasa Sourirajan developed the first practical membrane for a water desalting process called reverse osmosis. In 1975, Sidney Loeb was awarded a U.S. patent about the method and apparatus for generating power utilizing pressure-retarded-osmosis. Loeb's work seems to have the potential of large Scale Renewable Energy (LSRE) power generation application and will be discussed by the applicant of this present invention in greater detail at a later point.
While the history of osmosis goes back to 1748, no serious advancement has been yet achieved in employing this phenomenon in power generation.
However, osmosis starts to play significant role in separation processes despite the limited number of publications in this field. Osmosis is being used to treat industrial wastewaters, to concentrate landfill leachate and to treat liquid foods in the food industry. Recent developments in material science have also allowed the use of osmosis in controlled drug release. The main advantages of using osmosis are that it operates at low or no hydraulic pressures, it has high rejection of a wide range of contaminants, and it may have a lower membrane fouling propensity than pressure-driven membrane processes. Further, osmosis industrial processes require relatively simple basic equipment.
Very few U.S. patents in osmotic power generation were granted in the last four decades. The most significant U.S. Pat. No. 3,906,250, was granted to Loeb in 1975 and describes a method and apparatus for generating power by utilizing pre-retarded-osmosis and other embodiments for storing and using energy stored in the pressurized mixed solution.
U.S. Pat. No. 3,978,344, to Jellinek describes a process for generating energy by utilizing the osmotic pressure resulting when two liquids having different chemical potentials are placed in contact with opposite sides of the same semipermeable membrane. The process is particularly applicable to the production of energy from the system seawater/freshwater.
U.S. Pat. No. 4,193,267 to Loeb describes a method and apparatus for generating power utilizing pre-retarded osmosis as described in his earlier work, but with addition of means to convert the stored potential energy in the pressurized mixed solution to useful energy by depressurizing and re-pressurizing only the dilute solution.
In 2003, Finley, et al. were granted U.S. Pat. Nos. 6,313,545 and 6,559,554 for providing hydraulic power generation system for generating power using a pseudo-osmosis process which efficiently exploits the osmotic energy potential between two bodies of water having different salinity concentrations, but without the use of semipermeable membranes or other specially formulated material.
In 2007, Lampi, et al. were granted U.S. Pat. No. 7,303,674 disclosing a passive device that does not require energy input for using forward osmosis to generate significant hydraulic pressure that can be used to drive a reverse osmosis process.
U.S. Pat. No. 7,329,962 was granted to Alstot, et al. for a hydrocratic generator that is driven by the mixing of a relatively high salinity fluid with a relatively low salinity fluid.
Robert Mc Ginnis, et al, submitted an international Application No PCT/US2007/023541 for a method of converting thermal energy into mechanical work that uses a semipermeable membrane to convert osmotic pressure into electrical power. A closed cycle pressure-retarded osmosis (PRO) process known as osmotic heat engine (OHE) uses a concentrated ammonia-carbon dioxide draw solution to create high osmotic pressures which generate water flux through a semipermeable membrane against a hydraulic pressure gradient. The depressurization of the increased draw solution volume in a turbine produces electrical power. The process is maintained in steady state operation through the separation of the diluted draw solution into a re-concentrated draw solution and de-ionized water working fluid, both for reuse in an osmotic heat engine.
In recent years, Statkraft of Norway is assuming leading role in developing osmotic process for power generation from seawater. Statkraft is constructing a prototype to demonstrate that osmotic power actually works, and will be used to test the technology itself in the process of building the world's first complete facility for osmotic power generation. A full-scale commercial osmotic power plant could be in place as early as 2015 to supply enough electricity for almost 10,000 households.